Lumber grabbing apparatus

ABSTRACT

An apparatus for grabbing a material closely stacked in a compartment such as a hold, which is provided with means for smoothly and easily penetrating its grabbing arms into the interspace of the material so as to enable said grabbing arms to grab a large amount of the material at a time.

Tsuchihashi et al.

[451 Apr. 17, 1973 [541 LUMBER GRABIBIING APPARATUS 2,743,954 5/1956)stluno ..294/106 x l I [75] nventors Akira Tsuchl aS'hl' Kazuoll-llonma Primary Emmmer Gerald M. enza both of Tokyo, Japan AssistantExammerFrank E. Werner Assignfiei Hitachi, TOkYO, Japan Attorney-Craigand Antonelli [22] Filed: May 25, 197R [57] ABSTRACT 21 Appl. No.:146,636

An apparatus for grabbing a material closely stacked D 0 0 in acompartment such as a hold, which is provided [30] Apphcatmn Prion Datawith means for smoothly and easily penetrating its June 12, 1970 Japan..45 503|s grabbing arms the interspace of the material so as to enablesaid grabbing arms to grab a large amount of 52 us. (:1. ..294/88,294/106, 214/658 the malerlal at a [51] Int. Cl ..B66c 1/42 [58] Fieldof Search ..294/88, 106, 86.29

[ 56] References Cited 3 Claims, 4 Drawing Figures UNITED STATES PATENTS247,829 10/1881 Johnson ..294/83 PATENTEDAPR 1 1 727. 968

SHEET1'UF4 PR/OE ART INVENTORS PAQRR Tsuu-uaqsm am) \AHzuo ovum;

BY mug Mk. r AS L ATTORNEYS PATENTEUAPR 1 11915 5.727. 968

SHEEI 2 OF 4 FIG 2 INVENTORS BY (@4 NM r?\&& ATTORNEYS PATENTEDAPR1719753.727, 968

INVENTORS BY mm knma.

ATTORNEYS,

PATENTEU 1 71975 3.727, 968

SHEET 0F 4 1N VENTOR$ BY Qml HM er" NM ATTORNEY$ LUMBER GRABBINGAPPARATUS This invention relates to a grabbing apparatus capable ofgrabbing a large amount of material, e.g., lumbers, at a time bypenetrating its grabbing arms deep into the interspace of the lumbers.

A prior art grabbing apparatus well-known in the art, as shown in FIG.1, includes a grab 1 having a pair of cooperating grabbing arms 1a, 1b;a reciprocating cylinder unit 2 for opening and closing said grab 1; arotary cylinder unit 3 for rotating said grab 1 and anotherreciprocating cylinder unit 4 for moving the entire assembly of saidelements in a vertical direction; said grabbing arms la, lb of said grab1 being pivotally connected at their middle portions to said cylinderunit 2 by means of rods 5a, 5b respectively and also being pivotallyconnected at their roots to the lower end extremity ofa piston rod 2a ofsaid cylinder unit 2.

In the operation of the prior art apparatus described above, the pistonrod 2a of the reciprocating cylinder unit 2 is extended or retracted,whereby the grabbing arms 1a, lb are opened or closed to grab the logsT.

In such a prior artapparatus, however, when the grabbing arms la, lb areopened or closed by the cylinder unit 2, the tips of said grabbing arms1a, llb are displaced in a vertical direction. Namely, when the grabbingarms 1 a, lb are opened, the tips of said grabbing arms 1a, 1b moveoutwardly upwardly, whereas while they are closed, the tips thereofmoves inwardly downwardly.

Even with such grabbing arms, the logs stacked in a lumber yard orfloating on the water surface can be sufficiently grabbed, because thelogs are movable horizontally and hence the grabbing arms can be easilypenetrated into the interspaces of the logs.

However, with the amount of lumber being exported and importedincreasing in recent years, ships have been used for the transportationof the lumber and it is usual that the logs are closely stacked in ahold of the ship.

With the prior art apparatus, however, it is impossible to remove fromthe hold a large number of logs closely stacked in said hold at one timesince little space is available for the lateral movement of the logs dueto the limited space in the hold and, therefore, the amount ofpenetration into the stack of logs of the grabbing arms is small. Forgrabbing a large number of logs at a time, the apparatus itself must belarge in size.

The object of the present invention is to provide a lumber grabbingapparatus which is small in size and hence enables the weight of theentire loading machine to be reduced, and which is operable with highefficiency even in a narrow space.

FIG. 1 is a view showing the construction of a conventional lumbergrabbing apparatus;

FIG. 2 is a view showing the construction of the lumber grabbingapparatus according to the present invention;

FIG. 3 is a diagramshowing the hydraulic circuit of the lumber grabbingapparatus of the invention; and

FIG. 4 is a vertical sectional view of a position command pressurereducing valve used in the present invention.

The lumber grabbing apparatus of the invention is shown in FIG. 2.

Referring to FIG. 2, reference numeral 6 designates a grabbing apparatuselevating hydraulic cylinder, in which a piston 7 is slidably disposed.The piston 7 is connected to the lower end of a piston rod 8, the upperend of which is fixed to a machine frame. The fluid pressure in thecylinder varies incident to the vertical movement of the piston rod 8.Reference numeral 9 designates a grabbing apparatus rotating hydrauliccylinder and 10 generally designates a grab. The grab 10 includesgrabbing members 11, 11' and arms 12, 12, and said grabbing members andsaid arms are operable independently. Reference numeral 13 designates agrabbing members opening and closing hydraulic cylinder. The grabbingmembers 11, 11' are pivotally connected to the lower end of a piston rodof the cylinder 13 at one ends by means of a hinge pin 14. They are alsoconnected at their mid portions to one ends of rods 15, 15', the otherends of which are connected to the side walls of the cylinder 13respectively. Reference numerals 16, 16' designate rotary cylinders foropening and closing the arms 12, 12', and the arms can be pivotallymoved to the left and right by varying the fluid pressure in saidcylinders respectively.

Referring to FIG. 3 there is shown the hydraulic circuit of the subjectapparatus for operating the arms. The hydraulic circuit comprises amanually operable position command pressure reducing valve 17, a servodirectional control valve 18, the hydraulic cylinder 16, a positionfeedback pressure reducing valve 19, the arm 12 and pipes communicatingsaid elements with each other.

Now, each of the elements mentioned above will be described in detailhereunder: First of all, the servo directional control valve 18 includesa casing 20 which is provided with a port 20a communicating with a firstfluid pressure generator P1 of large capacity, a port 20b communicatingwith the position command pressure reducing valve 17, ports 20c and 20dcommunicating with ports 16a and 16b of the hydraulic cylinder 16respectively, a port 20 communicating with the position feedbackpressure reducing valve 19 and discharge ports 20f, 20g communicatingwith a tank (not shown). Reference numeral 21 designates a valve spoolslidably disposed in the casing 20, which has a land 21a forestablishing orbreaking the communication between the ports 20c and 20g,a land 21b for establishing or breaking the communication between theports 20a and 20d, and a land 210 for establishing or breaking thecommunication between the ports 20d and 20f.

The position command pressure reducing valve 17 which is operated by theoperator at his own will, is constructed as shown in FIG. 4. Namely,this pressure reducing valve 17 includes a casing 22 which is providedwith a port 22a communicating with a fluid pressure source, a port 2212communicating with the servo directional control valve 18, and a drainport 22c through which the pressurized fluid flowing into the casing 22from the port 22a is returned to the tank. In the casing 22 is slidablydisposed a valve spool 23 which has two lands 23a and 23b forestablishing or breaking the communication between the ports 22a and22b. A push rod 24 is inserted into the casing 22 on one side of thevalve spool 23 adjacent the land 23a and a spring 25 is provided betweensaid push rod 24 and said land 23a, by which the valve spool 23 isconstantly urged downwards. In the inner surface of the casing 22 areformed an annular groove 26 communicating with the port 22a and anannular groove 27 communicating with the port 22b.

A passage 29 is formed axially in the land 23b of the valve spool 23,for communicating a chamber 28 formed below the lower end of the valvespool 23, with the annular groove 26 and an orifice 30 is formed in saidpassage 29 at the central portion thereof.

Now, when the length I from the lower end of the position commandpressure reducing valve 17 to the top end of the push rod 24 isshortened by pushing said push rod, the valve spool 23 is moved down bythe spring 25, so that the communication is established between theports 22a and 22b and the pressurized fluid flows through the pipe toact on the servo directional control valve 18. On the other hand, thepressurized fluid in the annular groove 27 flows into the chamber 28through the orifice 30 to build up the pressure in said chamber againstthe biasing force of the spring 25. When the fluid pressure in thechamber 28 and the biasing force of the spring 25 are balanced by eachother, the valve spool 23 is located in a position to break thecommunication between the ports 22a and 22b. In other words, the fluidpressure in the port 22a is proportional to the amount of downwardmovement of the push rod 24.

Next, the arm opening and closing rotary cylinder 16 has a port 160communicating with the port c of the servo directional control valve 18and a port 16b communicating with the port 20d of said directionalcontrol valve 18. The arrangement is such that when the pressurizedfluid is supplied into the rotary cylinder 16 from the port 1611, anoutput shaft is connected directly with the arm is rotated in aclockwise direction, causing the arm in a clockwise direction, whereaswhen the pressurized fluid is supplied thereinto from the other port160, the output shaft is rotated in the opposite direction, causing thearm to rotate in a counterclockwise direction. The angle of rotation ofthe output shaft is limited to not more than 360.

The position feedback pressure reducing valve 19 is identical inconstruction with the position command pressure reducing valve 17previously described with reference to FIG. 4, and the outer end of apiston rod 19a of the valve 19 is held in contact with the side face ofthe arm connected to the output shaft of the rotary cylinder 16. Thepush rod is displaced in proportion to the angle of rotation a of thearm 12. Further, the position feedback pressure reducing valve 19 is incommunication with the first fluid pressure generator P1 and also withthe servo directional control valve 18 as will be described later.

The piping of the hydraulic circuit will be described with reference toFIG. 3. In FIG. 3, reference numeral 31 designates a pressurized fluidfeed pipe extending from a second fluid pressure generator P2 andconnected to the port 22b of the position command pressure reducingvalve 17, 32 a remote control pipe for feeding the pressurized fluidfrom the port 22a of the position command pressure reducing valve 17 tothe port 20b of the servo directional control valve 18 therethrough, and33 a pressurized fluid feed pipe extending from the first fluid pressuregenerator P1 to the port 20a of the servo directional control valve 18.

Reference numeral 34 designates a pipe communicating the port 20c of theservo directional control valve 18 with the port 16a of the rotarycylinder 16, 35 a pipe communicating the port 20d of the servodirectional control valve 18 with the port 16b of the rotary cylinder16, 36 a pipe branched from said pressurized fluid feed pipe 33 andconnected to the position feedback pressure reducing valve 19, and 37 apipe communicating the port 20e of the servo directional control valve18 with the position feedback pressure reducing valve 19.

In the above-described hydraulic circuit, when the position feedbackfluid pressure from the feedback pressure reducing valve 19 and thefluid pressure supplied from the position command pressure reducingvalve 17 into the right end chamber of the servo directional controlvalve 18 through the pipe 32 are equally balanced, i.e., when the valvespool 21 of the servo directional control valve 18 is in a neutralposition as shown in FIG. 3, the servo directional valve 18 does notsupply the pressurized fluid to either port of the rotary cylinder 16,so that the grab continues its grabbing motion when it is in thegrabbing operation or its opening motion when it is in the openingoperation.

The lumber grabbing apparatus of the invention will operate in thefollowing manner:

First of all, the rotary cylinder 9 shown in FIG. 2 is actuated to setthe arms 12, 12 in positions parallel to the longitudinal direction ofthe logs and at right angles to the surface of the ground, and then theloading machine is lowered to penetrate the arms 12, 12' into the firstlayer of logs. Successively thereafter, the arms 12, 12 are penetratedinto the second layer of logs. In this case, the angular positions ofthe arms 12, 12 are respectively adjusted by means of the rotarycylinders l6, 16 while holding the hydraulic cylinder 9 and the grabopening and closing cylinder 13 in the fixed state and lowering the grabelevating cylinder 6. The adjustment of the angle of opening a of eacharm 12 or 12' can be achieved by projecting or retracting the push rodof the position command pressure reducing valve 17. In more detail, whenthe valve spool 23 is moved down by pushing the push rod 24 in FIG. 4,the ports 22b and 22a are brought into communication with each other andthe fluid pressure from the second fluid pressure generator P2 shown inFIG. 3 is supplied through the pipe 32 into the right end chamber of theservo directional control valve 18 from the port 20b, causing theleftward movement of the valve spool 21. As a result, the communicationis established between the ports 20a and 20d and the fluid pressure fromthe first fluid pressure generator P1 is supplied into the port 16b ofthe rotary cylinder 16 through the pipe 35, causing the arms 12, 12 torotate in a clockwise direction. By the clockwise rotation of the arms12, 12, the push rod 19a of the position feedback pressure reducingvalve 19 in contact with said arm is moved, so that the valve spool ofsaid pressure reducing valve is displaced proportionally to the amountof displacement of said push rod 19a and the pressurized fluid flowsthrough the pipe 37 into the left end chamber of the servo directionalcontrol valve 18 from the port 20e, causing the valve spool 21 to moveto the right. The rightward movement of the valve spool 21 continuesuntil it reaches a position at which the fluid pressures in the rightend chamber and left end chamber of the directional control valve 18 areequally balanced. Namely, as the valve spool 21 moves to the right, thecommunication between the ports 20a and 20d is gradually broken and therightward movement of the valve spool 21 stops when the communication iscompletely broken and the fluid pressure in the left and right endchambers are balanced with each other.

When the pressure is removed from the push rod 24 of the positioncommand pressure reducing valve 17, the valve spool 23 in FIG. 4 isallowed to return its neutral position and the communication between theports 22b and 22a is broken. As a result, the fluid pressure in theright end chamber of the servo directional control valve 18 becomesgreater than that in the left end chamber thereof, causing the valvespool 21 to move to the right and thus the communication between theports 20a and 200 is established. The fluid pressure from the firstfluid pressure generator P1 is supplied through the pipe 34 into theport 160 of the rotary cylinder 16 and the arm 12 is rotated in acounterclockwise direction.

Incident to the rightward movement of the valve spool 21, thepressurized fluid in the right end chamber of the servo directionalcontrol valve 18 is returned to the position command pressure reducingvalve 17 through the pipe 32. Namely, the pressurized fluid isdischarged from the port 22a and flows into the lower end chamber 28through the orifice 30 of the valve spool 23 in FIG. 4. Consequently,the valve spool 23 is moved upwards and the land 23a opens the port 22c,whereupon the communication is established between the ports 22a and 22cand the pressurized fluid is slowly returned to the tank through theport 22c.

As the arm 12 rotates in a counterclockwise direction, the push rod 19aof the position feedback pressure reducing valve 19 is displaced andpressurized fluid supply into the pipe 37 is shut down by the valvespool. Therefore, the fluid pressure in the left end chamber of theservo directional control valve 18 is decreased and that in the rightend chamber thereof becomes higher, with the result that the valve spool21 moves to the left. The leftward movement of the valve spool 21continues until it reaches a position at which the pressures in theright and left end chambers are equally balanced. Namely, as the valvespool moves to the left, the communication between the ports 20a and 20dis slowly broken and, when the communication is completely broken, thefluid pressures in the right and left end chambers are balanced witheach other and the valve spool 21 stops its leftward movement.

As described above, the position of the valve spool 21 of the servodirectional control valve 18 is constantly changed by the axial movementof the push rod of the position command pressure reducing valve 17,directing the fluid pressure from the first fluid pressure generator P1to flow from the port 200 into the port 20c or 20d.

It will be understood, therefore, that by axially moving the push rod ofthe position command pressure reducing valve 17, the arm of the rotarycylinder 16 can be moved pivotally to the left and right and therebypenetrated into the second layer of logs.

After the arms have been penetrated deep into the 11, 11', whereby thelogs indicated by the hatched lines in FIG. 2 can be grabbed.

In comparing the prior art lumber grabbing apparatus of FIG. 1 with thatof the instant invention shown in FIG. 2, the former is slightly smallerin size than the latter but the latter can grab an amount of lumbertwice or more times as much as the amount which can be grabbed by theformer, at one time.

The number of logs which can be grabbed by the subject apparatus areindicated by the hatched lines, and the same number of logs areindicated in FIG. 1 by the solid lines.

In FIG. 1, the logs indicated by the cross-hatched lines are those whichcan be grabbed by the prior art apparatus but cannot be grabbed by theapparatus of FIG. 2 because the grabbing span is smaller than that ofthe former. From the comparison between the logs indicated by the solidlines and those indicated by the hatched lines, it will be understoodthat the apparatus of FIG. 2 can grab a larger amount of lumber at atime than the apparatus of FIG. 1, though it is relatively small insize.

According to the penetration type grabbing apparatus of the invention,the grab is composed of the grabbing members and the arms, and saidgrabbing members and arms are operable independently. Therefore, theapparatus of the invention can grab a large amount of article at onetime as compared with the logs by repeating the operation describedabove, the 2 cylinder 13 is actuated to close the grabbing membersconventional apparatus, even though the former is smaller in grabbingspan and in size than the latter. By employing the grabbing apparatus ofthe invention, the weight of the entire loading machine can be reducedand the operational efficiency of the machine can be enhanced even in anarrow space.

What is claimed is:

1. A lumber grabbing apparatus comprising a. a hydraulic cylinderincluding a piston slidably disposed therein and a piston rod connectedto said piston;

. a pair of grabbing members adapted to be opened and closed by saidhydraulic cylinder, each of said grabbing members having one endpivotally connected to the outer end of the piston rod of said hydrauliccylinder, the respective mid portions of said grabbing members beingpivotally connected to respective first ends of rods, the other ends ofsaid rods being connected to said hydraulic cylinder;

0. arms pivotally connected to the other ends of said grabbing membersrespectively; and

. hydraulic cylinders provided on said grabbing members respectively forcausing said arms to make a pivotal movement about the other ends ofsaid grabbing members.

2, A lumber grabbing apparatus comprising first hydraulic cylinder meanshaving a piston slidably disposed therein, a piston rod having one endconnected to said piston, a pair of grabbing members adapted to beopened and closed by said first hydraulic cylinder means, each of saidgrabbing members having one end thereof pivotally connected to the otherend of said piston rod, a pair of connecting rods, each connecting rodhaving one end connected to said first hydraulic cylinder means and theother end pivotally connected to the mid portion of a respective one ofsaid grabbing members, a pair of arms means, each of said 3. A lumbergrabbing apparatus according to claim arm means pivotally connected tothe other end of a 2, Whfir in aid nd hydraulic cylinder meansinrespective one of said grabbing members, and second cludes a P Ofhydraulic Cylinders, each of Said hydraulic cylinder means mounted onsaid grabbing hydraulic Q'W belng mounted on a respective one membersfor controlling the pivotal movement of said of Sald grabbmg members fcommnlflg the movearm means about the other end of said grabbing memmamof the arm means assoclated therew'thbers

1. A lumber grabbing apparatus comprising a. a hydraulic cylinderincluding a piston slidably disposed therein and A piston rod connectedto said piston; b. a pair of grabbing members adapted to be opened andclosed by said hydraulic cylinder, each of said grabbing members havingone end pivotally connected to the outer end of the piston rod of saidhydraulic cylinder, the respective mid portions of said grabbing membersbeing pivotally connected to respective first ends of rods, the otherends of said rods being connected to said hydraulic cylinder; c. armspivotally connected to the other ends of said grabbing membersrespectively; and d. hydraulic cylinders provided on said grabbingmembers respectively for causing said arms to make a pivotal movementabout the other ends of said grabbing members.
 2. A lumber grabbingapparatus comprising first hydraulic cylinder means having a pistonslidably disposed therein, a piston rod having one end connected to saidpiston, a pair of grabbing members adapted to be opened and closed bysaid first hydraulic cylinder means, each of said grabbing membershaving one end thereof pivotally connected to the other end of saidpiston rod, a pair of connecting rods, each connecting rod having oneend connected to said first hydraulic cylinder means and the other endpivotally connected to the mid portion of a respective one of saidgrabbing members, a pair of arm means, each of said arm means pivotallyconnected to the other end of a respective one of said grabbing members,and second hydraulic cylinder means mounted on said grabbing members forcontrolling the pivotal movement of said arm means about the other endof said grabbing members.
 3. A lumber grabbing apparatus according toclaim 2, wherein said second hydraulic cylinder means includes a pair ofhydraulic cylinders, each of said hydraulic cylinders being mounted on arespective one of said grabbing members for controlling the movement ofthe arm means associated therewith.